Image processing apparatus for transmitting compressed area information to be used at editing

ABSTRACT

In an image processing method, image information described by a page descriptor language is developed by the page descriptor language into a form not pasted with to-be-pasted image information, without reading out, for image development, the to-be-pasted image information from a unit for storing the to-be-pasted image information. The image information in the form not pasted with the to-be-pasted image information and the to-be-pasted image information are separately transmitted to a printer. The image information in the form not pasted with the to-be-pasted image information is compressed by reversible coding. The to-be-pasted information is compressed by irreversible coding.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an image processing apparatussuch as a host computer for transferring image information or an imageoutput apparatus for forming images in accordance with imageinformation.

[0003] 2. Related Background Art

[0004] In a system in which a host computer is connected to a printer,one image output method is to transfer to the printer the program of apage descriptor language (to be abbreviated as a PDL hereinafter) formedby an application or the like of the host computer, develop the PDL intoa bit image by a controller of the printer, and send the bit image to aprinter engine, thereby outputting an image.

[0005] In the above method, in order to paste a natural image read by ascanner or the like into a line drawing described by, e.g., a graphicinstruction of the PDL, information indicating the natural image istransferred as a file independently of the program of the PDL, and theprogram of the PDL containing a command for specifying the file and acommand for specifying a position in which the natural image is to bepasted is transferred to the printer. The printer executes the pastingprocessing by decoding these commands.

[0006] Another output method is to develop the PDL into a bit image inthe host computer and transfer the bit image to the printer, therebyoutputting an image without executing any processing in the printer.This method requires, in the host computer, a CPU with a satisfactoryprocessing capability, a memory with a large capacity, and a hard diskwith a capacity large enough to temporarily store the developed bitimage. An I/F with a speed high enough to send a bit image with a largecapacity is also necessary between the host and the printer.

[0007] In order to paste the natural image into the line drawing by thismethod, the host computer holds information representing the naturalimage as a file and decodes the program of the PDL including a commandfor specifying the file and a command for specifying a position in whichthe natural image is to be fitted, thereby generating a bit map image inwhich the natural image is pasted in the line drawing. The bit map imagethus formed is transferred to the printer.

[0008] The former method, however, has a drawback that the cost of theprinter as a whole increases because the controller is incorporated.

[0009] The drawback of the latter method, on the other hand, is that thehost computer is required to have a high processing ability, and a framebuffer for storing a bit image of one page is sometimes necessary on theprinter side unless a special I/F with a very high transfer rate isused. This results in a very high cost of the memory. In order totransfer image data by using an I/F with a low transfer rate withoutproviding any printer buffer on the printer side, a bit map image formedby the host computer may be compressed before being transferred to theprinter and then expanded on the printer side. There has been proposed,however, no method of preferably compressing an image in which a naturalimage is pasted in a line drawing.

SUMMARY OF THE INVENTION

[0010] It is an object of the present invention to eliminate thedrawbacks of the above conventional techniques and provide an imageprocessing apparatus capable of transferring image information at a highefficiency.

[0011] In order to achieve the above object, an image processingapparatus of the present invention is characterized by comprising outputmeans for outputting image information to be used in editing and areainformation for performing editing by using the image information, andtransmitting means for transmitting the image information and the areainformation output from the output means, wherein the output meansoutputs the area information developed for each image in the form ofcompressed data.

[0012] In addition, an image processing apparatus of the presentinvention is characterized by comprising generating means for generatingfirst image information representing a natural image, second imageinformation representing a line drawing, and area information forperforming editing by using the first image information and the secondimage information, and encoding means for synthesizing the second imageinformation and the area information generated by the generating meansand encoding the synthesized information.

[0013] Furthermore, an image processing apparatus of the presentinvention is characterized by comprising a host computer for processingimage information, and a printer for forming a visible image of theimage information processed by the host computer, wherein the hostcomputer performs irreversible compression for image informationrepresenting a natural image in units of pixels and reversiblecompression for image information representing a line drawing in unitsof pixels, and transmits the compressed image information to theprinter.

[0014] According to the present invention, in decoding and developing apage descriptor language containing a paste command for imageinformation (to be referred to as to-be-pasted image informationhereinafter) compressed as a file by irreversible coding or the like,this page descriptor language is developed into image information (i.e.,line drawing information to be referred to as image informationsubjected to pasting with the to-be-pasted image informationhereinafter) in a form not pasted with the above to-be-pasted imageinformation. The image information subjected to pasting with theto-be-pasted image information can be compressed at a high efficiency bythe irreversible coding. The to-be-pasted image information iscompressed at a high efficiency with little image degradation by theirreversible coding.

[0015] The to-be-pasted image information and the image informationsubjected to pasting with the to-be-pasted image information, therefore,can be transferred efficiently because they are transferred separately.

[0016] A command contained in the page descriptor language program andindicating a position at which the to-be-pasted image information is tobe pasted includes write start position information (a point at theupper right corner of the to-be-pasted image information), lateral widthinformation, and longitudinal width information. A layout plane in theform of a bit map is formed by decoding these pieces of information.This layout plane can be compressed at a high efficiency by the sameirreversible coding as of the image information subjected to pastingwith the to-be-pasted image information.

[0017] If, therefore, a common encoding circuit is usedtime-divisionally, the image information subjected to pasting with theto-be-pasted image information and the layout plane can be encodedwithout providing any additional encoding circuit.

[0018] Other objects, advantages, and effects of the present inventionwill become apparent from the accompanying drawings, the followingdetailed description, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a block diagram showing the arrangement of the firstembodiment of an image output system according to the present invention;

[0020]FIG. 2 is a view showing an example of a document to be formed;

[0021]FIG. 3 is a view for explaining areas in which text informationand image information are decoded;

[0022]FIG. 4 is a block diagram showing the arrangement of an image areadesignating unit shown in FIG. 1;

[0023]FIG. 5 is a block diagram showing the arrangement of the secondembodiment of the present invention;

[0024]FIG. 6 is a view for explaining a layout plane;

[0025]FIGS. 7A, 7B, and 7C are views for explaining a state in which animage to be pasted is varied;

[0026]FIG. 8 is a view for explaining the varying conditions in FIGS. 7Ato 7C;

[0027]FIG. 9 is a block diagram showing the arrangement of the thirdembodiment of the present invention;

[0028]FIGS. 10A, 10B, and 10C are views for explaining a state in whichan image to be pasted is rotated;

[0029]FIGS. 11A and 11B are views for explaining an order of pixels tobe encoded;

[0030]FIG. 12 is a block diagram showing the arrangement of the fourthembodiment of the present invention;

[0031]FIG. 13 is a view for explaining a layout plane;

[0032]FIG. 14 is a view showing the relationship between the layoutplane and the text information;

[0033]FIG. 15 is a block diagram showing the arrangement of an imageidentifying circuit according to the fourth embodiment;

[0034]FIG. 16 is a view showing the way a plurality of pieces of imageinformation are stored in an image memory;

[0035]FIG. 17 is a block diagram showing the arrangement of the fifthembodiment of an image output system according to the present invention;

[0036]FIG. 18 is a view showing an order of transfer of a plurality ofimages according to the fifth embodiment;

[0037]FIG. 19 is a block diagram showing the arrangement of the sixthembodiment of an image output system according to the present invention;

[0038]FIG. 20 is a view showing all information to be transferredaccording to the sixth embodiment;

[0039]FIG. 21 is a block diagram showing the arrangement of the seventhembodiment of an image output system according to the present invention;

[0040]FIG. 22 is a block diagram showing the arrangement of the eighthembodiment of the present invention;

[0041]FIGS. 23A to 23E are views for explaining layout planes accordingto the eighth embodiment;

[0042]FIG. 24 is a schematic view showing an image memory;

[0043]FIG. 25 is a flow chart for forming a layout plane according tothe ninth embodiment of the present invention;

[0044]FIGS. 26A and 26B are views showing layout planes according to theninth embodiment;

[0045]FIG. 27 is a block diagram showing the arrangement of the tenthembodiment of the present invention;

[0046]FIG. 28 is a view showing SOI plane information of a document;

[0047]FIG. 29 is a view showing an image identification signalgenerating unit 5115 shown in FIG. 27;

[0048]FIGS. 30A to 30C are views showing layout plane information, SOIplane information, and image numbers given to images of a documentincluding three images;

[0049]FIG. 31 is a block diagram showing an image identification signalgenerating unit according to the eleventh embodiment of the presentinvention;

[0050]FIG. 32 is a block diagram showing the twelfth embodiment of thepresent invention;

[0051]FIG. 33 is a block diagram showing the function of an imagemanager;

[0052]FIG. 34 is a block diagram showing the function of a devicedriver;

[0053]FIG. 35 is a block diagram showing the function of an enginecontroller; and

[0054]FIG. 36 is a block diagram showing a device driver according tothe thirteenth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] The preferred embodiments of the present invention will bedescribed in detail below with reference to the accompanying drawings.

1st Embodiment

[0056] The first embodiment of the present invention will be describedbelow with reference to FIG. 1.

[0057]FIG. 1 is a block diagram schematically showing a system in whicha host computer is connected to a printer by an interface cable 206.Assume that the host computer supplies to the printer a documentcontaining characters or a line drawing (to be referred to as a texthereinafter) and a natural image (to be referred to as an imagehereinafter) obtained by reading an original by using, e.g., an imagereader, and the printer outputs this document. The text is generated bydecoding the description of a PDL program 200. Image information iscompressed by a compressing means at a high compression ratio and storedin a hard disk (201 in FIG. 1) of the host computer. An example of thiscompressing means is high-efficiency compressing means proposed by theJPEG (Joint Photographic Expert Group).

[0058] The PDL program describes only layout information indicating aposition of a page at which the image is to be pasted. As shown in FIG.2, the layout information is designated by the write start position (thecoordinate in a main-scanning direction: Xs, the coordinate in asub-scanning direction: Ys) of the image, and the dimensions (thelateral width: WIDTH, the longitudinal width: HEIGHT) of the image. ThePDL program is developed into a bit image by a rasterizer 202. At thesame time, layout information of the image is generated by decoding thePDL program. At this point, however, no processing for pasting the imageinto the text is performed. The bit image information developed by therasterizer is subjected to compression performed by an encoding unit 204by using a coding scheme such as arithmetic coding or run-length codingsuitable for the text.

[0059] The information of the text and the image thus compressed and thelayout information of the image are selected by a selector 205 andtransferred to the printer at a predetermined timing. A selector 207 ofthe printer is switched at a predetermined timing to store the textinformation in a text memory 208 and the image information in an imagememory 209. The layout information is input to an image area designatingunit 210.

[0060] The information of the compressed text and the information of thecompressed image are decoded by decoding units 211 and 212,respectively. As shown in FIG. 3, the text is decoded constantly, butthe timing of decoding of the image must be controlled because the imagedecoding is performed only in an image area. An image area designatingunit 210 performs this control.

[0061]FIG. 4 shows the details of this image area designating unit 210.A portion surrounded by dotted lines in FIG. 4 corresponds to the imagearea designating unit 210 shown in FIG. 1. Xs, Ys, WIDTH, and HEIGHTcontained in the layout information input from the host computer are setin registers 503, 504, 506, and 507 by switching a selector 501 atpredetermined timings. A main-scanning direction counter 502 and asub-scanning direction counter 505 perform count operations as decodingproceeds. That is, the resultant counts represent coordinates in a pagecurrently being decoded. The count of the main-scanning directioncounter 502 and the value of Xs set in the register 503 are input to acomparator 510. If the count A and the value B of Xs satisfy A≧B, thecomparator outputs a signal at level High. An adder 508 adds the dataset in the registers 503 and 504 and inputs the sum to a comparator 511.If the count A and the sum B satisfy A≧B, the output from the comparator511 goes High. This output is input to a NOT circuit 515. That is, theoutput signal from this NOT circuit 515 goes High only when A<B isestablished in the comparator 511. The identical processing is alsoperformed in the sub-scanning direction. The resultant outputs from thecomparators 510 and 511 and comparators 512 and 513 and the invertedsignals of these outputs are input to an AND circuit 514. With the aboveprocessing, the output from the AND circuit 514 goes High only in theimage portion represented as a hatched portion in FIG. 3. That is, theimage area designating unit shown in FIG. 4 can generate a signal whichgoes High only while the image area is decoded, and the decoding unit212 for decoding images shown in FIG. 1 can be controlled by using thissignal. This signal is also input to a selector 213 to selectivelysupply the text information and the image information to a printerengine 214.

[0062] With the above arrangement, even if a document has both a textportion and an image portion, the information quantities of the textportion and the image portion can be reduced by the two discretecompressing means respectively suitable for compressing texts andimages. This largely reduces the capacity of the frame buffer of theprinter.

2nd Embodiment

[0063] In the system shown in FIG. 1, however, the configuration of theimage area designating unit is complicated as shown in FIG. 4, and thissometimes increases the load of processing during decoding. In addition,in order to process a page having a plurality of images, it is necessaryto prepare a plurality of registers for storing a plurality of pieces oflayout information or to perform processing of temporarily storing aplurality of layout information in a memory and sequentially reading outthe information from the memory. A plurality of counters and a pluralityof comparators are also required, resulting in a complicated hardwarearrangement in some cases.

[0064]FIG. 5 is a block diagram showing the arrangement of the secondembodiment of the present invention.

[0065] A PDL (page descriptor language) 101 is a block for describingdocument descriptor instructions for, e.g., characters, graphics, andimages in a predetermined form of a language. In order to synthesize anatural image or an existing image file, such as CG (computer graphics),with characters and graphics in one page of a document, the PDLgenerates a description for designating an area in which the image to besynthesized is to be fitted.

[0066] A rasterizer 102 decodes the document descriptor instructionformed by the PDL 101 and converts the instruction into a dot indicationsignal. In this case, a text image need not be a binary one but may be aso-called multilevel text image having gradation information in eachpixel. In the case of the multilevel text image, the circuitconfiguration need only be so designed as to hold bit maps in an amountrequired to express the gradation information in a one-to-onecorrespondence with bit planes.

[0067] For a portion designated as an image pasting area by the PDL 101,a layout plane indicating that area is generated (by a layout planegenerating unit 11).

[0068] The generation of this layout plane is the characteristic featureof this embodiment.

[0069] The layout plane will be described with reference to FIG. 6.

[0070] Suppose, as an example of a document to be formed, that an imagefile is to be pasted in the same page as characters and graphics asshown in FIG. 2.

[0071] An area in which this image file is to be pasted is a portionsurrounded by dotted lines. A bit map as shown in FIG. 6 is generated inaccordance with a description concerning this image area in the PDLprogram. This bit map has the same resolution as that of a bit mapdeveloped by the rasterizer 102; that is, “1” is placed at each pixel inan area in which the image is to be fitted, and “0” is placed at eachpixel in an area except for the image area.

[0072] Subsequently, an encoding unit 103 encodes the bit map generatedby the rasterizer 102 and the layout plane generated by the layout planegenerating unit 11 for the purposes of, e.g., shortening the transfertime in a transmission path (between a host computer and a printer) andreducing the capacities of memories required on the printer side.Although this coding scheme is not particularly limited, reversiblecoding, such as arithmetic coding or MMR, is preferred. Since the layoutplane indicates only the image area, the number of change points issmall, and so a very high coding efficiency can be expected. That is, anincrease in code amount resulting from the addition of the layout planeis very small.

[0073] Assume, in this embodiment, that the image to be pasted in thedesignated area is an image file already formed by another applicationsoftware and stored in a memory unit of the host computer after beingcompressed by a compression format of, e.g., the JPEG. The designatedimage file is transmitted to the printer without being decoded and, asin the first embodiment, stored in a image memory 106 incorporated inthe printer.

[0074] The information (text information), such as characters and a linedrawing, and the layout information both encoded by the encoding unit103 are stored in a text memory 105 incorporated in the printer.

[0075] Suppose the capacity of each of the two types of internalmemories of the printer is smaller than the full memory of one outputpage, that is:

(the number of all pixels of the maximum output size of theprinter)×(the number of gradation levels per pixel)

[0076] In the printer, decoding of the text is started in synchronismwith the output timing of a printer engine 112. The decoding and theoutput from the printer engine must be synchronized because it isdifficult to stop the printing operation once the operation is startedif the printer according to the present invention is, e.g., a laser beamprinter, an LED printer, or a liquid crystal printer.

[0077] The decoding of the text memory is preferably not bit planesequential decoding but pixel sequential decoding even if the characterinformation or the graphic information is multilevel information.

[0078] The layout information is also processed as one bit informationat the same pixel of the text information and is preferably decodedearlier by several pixels than the text information in actualprocessing.

[0079] The decoded layout information is transmitted to an imagedecoding unit 110. The image decoding unit 110 is a unit for decodingimages compressed by the host computer and stored in the image memory ofthe printer.

[0080] The image decoding unit 110 starts decoding only when the layoutinformation is “1”, i.e., does not perform decoding when the layoutinformation is “0”.

[0081] The same layout information is also transmitted to a switch 111.When the layout information is “0,” the switch 111 is closed to aterminal A to select output of the text information. When the layoutinformation goes to “1”, the switch 111 is closed to a terminal B toselect output of the decoded image information.

[0082] As described above, holding all the pixels of the layoutinformation by the bit map makes switching between the text informationand the image information very easy.

[0083] Other effects obtained by this embodiment will be describedbelow.

[0084]FIG. 7A shows a document to be formed by the host computer in thesame manner as described above. Assume that an existing image fileformed by another application software is also to be pasted in the samepage as characters and graphics in this document to be formed. Thisimage file is originally a rectangular image as shown in FIG. 7B andstored in the storage unit of the host computer after being encoded by acompression scheme of, e.g., the JPEG.

[0085] Assume the image is varied on the document to be formed asindicated by dotted lines in FIG. 7A. FIG. 7C illustrates a portion (thestart position of an area of the image to be fitted) of a layout planerepresenting this varied image area. Referring to FIG. 7C, a portionwhere “1”s are arranged indicates the image pasting area, and a portionwhere “0”s are arranged indicates an area except for the image pastingarea. In this manner, even if an image is thus varied, generating thelayout plane makes it possible to transmit an image file other than arectangular image to the printer while the file is kept compressed,which is difficult to perform by conventional systems.

[0086] Such variation, however, is based on the assumption, as shown inFIG. 8, that the lateral width (WIDTH) and the longitudinal width(HEIGHT) of the image remain unchanged after the variation, and an orderof transfer of pixels of the image is the same as a raster order afterthe variation.

[0087] The printer need only decode the image in accordance with layoutinformation in the same manner as described above such that the decodedimage information is pasted in a portion in which the layout plane is“1”. This effect, therefore, can be realized by the same arrangement asdescribed above.

3rd Embodiment

[0088]FIG. 9 shows the third embodiment of the present invention. Thisembodiment realizes rotation of an image which is difficult to performin the above embodiments.

[0089]FIG. 10A illustrates a document to be formed in this thirdembodiment, in which a portion surrounded by dotted lines indicates animage to be fitted. As in the above embodiments, an image file which isoriginally the one shown in FIG. 10B is rotated by application softwareand fitted.

[0090]FIG. 10C shows a portion of a layout plane. Referring to FIG. 10C,points indicated by “1” represent pixels in which the image file is tobe fitted, and points indicated by “0” represent other pixels.

[0091] In this document to be formed, since the image to be pasted isrotated as described above, the raster direction of the image filestored is different from the raster direction after the image is fitted.To realize this processing by using the arrangement shown in FIG. 5,therefore, it is necessary to provide a large-capacity buffer memory inthe printer to develop and store the decoded image information in pixelpositions corresponding to the layout plane in the buffer memory. Thisextremely increases the load of the printer.

[0092] For this reason, the arrangement shown in FIG. 9 is used in thisembodiment.

[0093] Referring to FIG. 9, a compressed image 2104 indicates an imagecompressed by a compression scheme of, e.g., the JPEG, as in the secondembodiment described above. A decoding unit 2051 is a unit for decodingthis compressed image, which decodes the image in a host computer.

[0094] An encoding unit 2052 encodes the image information once decoded.

[0095] This encoding unit 2052 performs coding in accordance with not acoding scheme in which coding is performed in units of blocks, such asthe scheme employed by the JPEG but a coding scheme, such as DPCM, inwhich coding can be performed in units of pixels. An order of pixels tobe encoded is not an order in the raster direction of the stored imagebut an order in the raster direction of the rotated image.

[0096] This order of pixels will be described below with reference toFIGS. 11A and 11B. FIG. 11A is a view similar to FIG. 10C, in which aportion of the layout plane formed by the document shown in FIG. 10A isillustrated. FIG. 11B shows an order of pixels to be encoded inaccordance with the input information of this layout plane.

[0097] An image decoding unit of the printer is of course a decodingunit corresponding to the encoding unit 2052.

[0098] The arrangement of this embodiment can realize not only rotationbut also any variation of an image.

[0099] In addition, the compressed image 2104 is already compressedbefore being stored in this embodiment, but the image need not be thecompressed one. In such a case, the decoder 2051 is unnecessary in thisembodiment.

4th Embodiment

[0100] In the fourth embodiment of the present invention, to obtainlayout information of a plurality of image parts, text data is added toa layout plane for designating the locations of the image portions in ahost computer and then transferred to a printer. The printer has a unitfor controlling decoding of the image by using the information of thelayout plane when the decoding is performed. This arrangement of thefourth embodiment facilitates decoding processing in the printer andalso simplifies the hardware configuration.

[0101]FIG. 12 is a block diagram showing an image output apparatusaccording to the fourth embodiment of the present invention. FIG. 12illustrates a system in which the host computer is connected to theprinter in the form of simple blocks as in FIG. 5. Blocks having thesame functions as in FIG. 1 are not particularly explained in thisembodiment.

[0102] The layout information of an image described in a PDL is appliedto a layout plane generating unit 1103. The layout plane is a bit planeconstituted by 1-bit pixels, as shown in FIG. 13, in which a text areahas level “0” and an image area has level “1”. The layout planegenerating unit 1103 generates this layout plane in accordance with theinput layout information. Even if a plurality of images are present,image areas are formed on one bit plane from the layout information ofthe individual images as shown in FIG. 13.

[0103] The layout plane thus generated is input to an encoding unit 1104and compressed by using reversible coding, such as arithmetic coding orrun-length coding, like the text part. The layout plane can becompressed at a high compression ratio even by the reversiblecompression as described above because of the nature of the layoutplane. Therefore, the information quantity of the layout informationitself to be transferred to the printer is very small.

[0104] The layout plane is encoded by using (n+1) bits obtained byadding one bit of the information of the layout plane to n bitsindicating the color information of the text, as shown in FIG. 14. Thetext and the layout plane are stored together in a text memory 1108 evenafter being encoded. In the addition of this layout plane, if the bit ofthe layout plane is 0 as shown in FIG. 14, i.e., if the pixel indicatesa text, the color information of the text is set in n bits of the textpart. If the bit of the layout plane is 1, i.e., if the pixel indicatesan image, no color information is necessary because a compressed image1101 contains color information provided that overlap of the image andthe text is not taken into account. Therefore, by taking intoconsideration a case in which a plurality of images are to be pasted,information for identifying a plurality of images is added to the textpart. A rasterizer 1102 performs processing of adding thisidentification information. The image identification information is, forexample, information having an order of transfer of images from the hostcomputer in the form of numerical values. That is, the information bywhich the printer can identify uniquely a plurality of images is set inplace of the color information of the text. In this arrangement, amethod of identifying images naturally requires providing an identifyingmeans in the printer.

[0105] The information of the text and the information of the image bothcompressed by the host computer are stored in respective correspondingmemories of the printer. In this case, the image may be stored in a harddisk or the like of the host computer after being compressed asdescribed above in the conventional examples. Alternatively, anuncompressed image may be subjected to rasterization and compression atthe same time while being transferred to the printer.

[0106] The text, the image, and the layout plane are decoded by decodingunits 1111 and 1112. The decoding unit 1111 performs decodingconstantly. The (n+1)-bit text information and the layout plane decodedby the decoding unit 1111 are supplied to an image identifying circuit1113.

[0107]FIG. 15 is a block diagram showing the image identifying circuit1113. Of the input information of the text and the layout plane, n bitsof the text information are applied to a decoder 802. Simultaneously,1-bit data of the layout plane is also input to the decoder 802 througha signal line 801. In this case, control is performed such that thedecoder 802 operates when the signal is High, i.e., when the image is tobe decoded. In accordance with the image identification method describedabove, when the number supplied from the host computer is the value ofthe image identification information, the decoder 802 outputs a memoryaddress indicating a position of the image memory at which an image ofthe number designated by that value is stored. Assume that three imagesA, B, and C are transferred in this order from the host computer andstored in the image memory as shown in FIG. 16. In decoding the image A,a value “1” is set in the image identification information. On the basisof this value, the decoder 802 shown in FIG. 15 outputs the head addressof a memory area of an image memory 1109 shown in FIG. 12 in which theimage A is stored. The same processing is performed in identifying theremaining images B and C.

[0108] The output memory address signal from the image identifyingcircuit 1113 is input to a memory control unit 1110. In this memorycontrol unit 1110, pointers indicating memory areas in which individualimages are stored are managed in units of images. The memory controlunit 1110 with this function determines which image is to be read inaccordance with the input address information, and outputs a memoryaddress indicating a pointer corresponding to the image thus determined.This memory address is input to the image memory 1109, and data of thecorresponding image is read out from the memory and input to thedecoding unit 1112.

[0109] The layout plane is also used in controlling image decoding. Thatis, one bit of the layout plane information is input from a signal line1114 to the image decoding unit 1112. Since data of the layout plane is“0” in the text part, no image decoding is performed for that part.Since, on the other hand, data of the layout plane is “1” in the imagepart, image decoding is performed for the image part. The layout planeis also input to a selector 1115 to selectively output the decoded dataof the text and the image to a printer engine 1116.

[0110] According to this embodiment, the layout information required indecoding of images can be obtained easily with a simple hardwareconfiguration.

5th Embodiment

[0111]FIG. 17 is a block diagram showing the fifth embodiment of thepresent invention. FIG. 17 illustrates in the form of simple blocks asystem in which a host computer is connected to a printer in the form ofsimple blocks, like FIG. 12 showing the fourth embodiment. Blocks withthe same functions as in the fourth embodiment are not particularlydescribed in this embodiment.

[0112] In outputting a plurality of images, if images are present on thesame line in the main-scanning direction as shown in FIG. 6, the imageidentifying processing as in the fourth embodiment described above mustbe performed. If, on the other hand, no images overlap in themain-scanning direction as shown in FIG. 18, these images aretransferred from the host computer in an order of numbers shown in FIG.18. In this case, when these images are to be decoded in the printer,they can be read out in the order by which they are stored in an imagememory, so the above image identifying processing need not be performed.Since, however, it is necessary to designate image areas in outputtingthe document, one color of text color information is used as informationfor designating the image areas in this embodiment. For example, whendata indicating the text color information consists of n bits, 2^(n)colors can be expressed. Since one of these colors is assigned as theinformation for designating the image areas, a total of 2−1 colors canbe expressed.

[0113] A rasterizer 1002 shown in FIG. 17 develops the text part of thetext information into a bit image and, in the image part, assigns apredetermined color (e.g., white) of the text color information as theinformation for detecting the image areas.

[0114] As in the fourth embodiment, the text information and thecompressed image subjected to the encoding processing are transferred tothe printer and stored in a text memory 1008 and an image memory 1009,respectively. The text information and the compressed image are decodedby decoding units 1011 and 1012, respectively, when the document is tobe output. Decoding of the text is performed constantly, and the decodedresult is input to an image detecting unit 1013. The image detectingunit 1013 detects the color (to be referred to as an image area colorhereinafter) assigned to detect image areas by the host computer. Uponreceiving the image area color, the image detecting unit 1013 supplies acontrol signal to the image decoding unit 1012, performing decoding ofthe images. This control signal is also input to a selector 1015 toselectively output the text information and the image information to aprinter engine 1016.

[0115] With the above arrangement of this embodiment, image areas can bedesignated by assigning one color of the text color information becauseno image identification need be performed if images do not overlap inthe main-scanning direction. In this embodiment, the function of thelayout plane is executed by the image area color, so the layout planeneed not be transferred in addition to the text information. As aresult, the memory capacity can be reduced accordingly.

6th Embodiment

[0116]FIG. 19 is a block diagram showing the sixth embodiment of thepresent invention. FIG. 19 illustrates in the form of simple blocks asystem in which a host computer is connected to a printer, like FIG. 12showing the forth embodiment. Blocks with the same functions as in thesecond embodiment are not particularly described in this embodiment.

[0117] In outputting a plurality of images, these images need not bediscriminated from one another if they do not overlap in themain-scanning direction as in the fourth embodiment. In this embodiment,therefore, transfer of image part information of text information isomitted by the use of a layout plane. This can reduce a wholeinformation quantity transferred from the host computer to the printer.That is, as shown in FIG. 20, nothing is transferred as data for areasindicated by hatched portions in the text information.

[0118] Referring to FIG. 19, as in the fourth embodiment, layoutinformation described in a PDL 1200 is input to a layout planegenerating unit 1203 to generate a layout plane. This layout plane isencoded by an encoding unit 1205, and the encoded data is transferredtogether with texts and images to the printer. These text data, layoutplane data, and image data are stored in a text memory 1209, a layoutmemory 1210, and an image memory 1211, respectively.

[0119] In performing decoding, a decoding unit 1213 for decoding layoutplanes operates constantly. The decoded result is applied to decodingunits 1212 and 1214 for decoding texts and images, respectively, therebycontrolling decoding. That is, when the text part is to be decoded, “0”is output as the data of the layout plane. Therefore, a NOT circuit 1215supplies a signal at level “High” to the decoding unit 1212, startingdecoding of the text information. At this point, the decoding unit 1214for decoding images performs no decoding because a signal at level “Low”is input. When the image information is to be decoded, “1” is output asthe data of the layout plane. Therefore, a signal at level “High” isinput to the image decoding unit 1214, and, in contrast, a signal atlevel “Low” is input to the text decoding unit 1212, thereby executingdecoding of the image information alone. The layout plane is also inputto a selector 1216 to selectively output the text information and theimage information to a printer engine 1217.

[0120] With the above arrangement of this embodiment, the use of thelayout plane makes it possible to control decoding of the textinformation and the image information performed in the printer. Thismakes transfer of the image part text information unnecessary, reducinga quantity of information to be transferred and also reducing thecapacity of the memory for storing texts.

7th Embodiment

[0121]FIG. 21 is a block diagram showing the seventh embodiment of thepresent invention. FIG. 21 illustrates in the form of simple blocks asystem in which a host computer is connected to a printer, like FIG. 12showing the fourth embodiment. Blocks with the same functions as in thefourth embodiment are not particularly described in this embodiment.

[0122] In outputting a plurality of images, no discrimination need beperformed between these images it they do not overlap in themain-scanning direction as in the fifth and the sixth embodiments. Inthis embodiment, therefore, there is provided a unit for embeddinginformation for changing the attribution of an image into n bitsrepresenting the color information of a text for an image part of textinformation by the use of a layout plane.

[0123] Referring to FIG. 21, a decoding unit 1410 for decoding textsoperates constantly in decoding. The outputs from the decoding unit 1410are n bits of text data and one bit of layout plane data. The layoutplane is input to a decoding unit 1411 for decoding images, therebycontrolling decoding. The image data thus decoded is applied to an imageattribution change circuit 1412, and at the same time the decoded textdata is also input to the image attribution change circuit 1412. Thisimage attribution change circuit 1412 has, for example, a circuitconfiguration capable of changing the density of an image. The imageattribution change circuit 1412 with this configuration, therefore, canchange the density of an image when a value representing the level of adensity is set by the host computer in text data to be input to thecircuit 1412. The image data changed by the image attribution changecircuit 1412 is input to a selector 1413. The layout plane data is alsoinput as a control signal to the selector 1413 to selectively output thetext data and the image data to a printer engine 1414.

[0124] In addition, by changing the configuration of the imageattribution change circuit, it is possible to perform processing of,e.g., changing the color balance of an image or shading an image.

[0125] With the above arrangement of this embodiment, the informationfor changing the attribution of an image can be embedded in the data ofthe image part of text information by the use of a layout plane, andthis makes effective use of the data possible. In addition, thisarrangement enables processing of changing the attribution of only animage, which is impossible by conventional systems.

[0126] According to the fourth to the seventh embodiments of the presentinvention as described above, in an image output system in whichcharacters and line drawings to be developed into bit images by a hostcomputer and compressed natural images are transferred separately to aprinter and stored in a frame buffer memory, and image output isperformed in accordance with a printer engine, a processing circuit forarranging a plurality of natural images at predetermined positions canbe constituted easily. In addition, since information to be transferredto the printer to perform this processing is compressed, the transferprocessing time can be shortened, and the memory capacities of theprinter can also be reduced.

8th Embodiment

[0127] The eighth embodiment of an image processing apparatus accordingto the present invention will be described in detail below withreference to FIGS. 22 and 23A to 23E.

[0128] Referring to FIG. 22, a portion surrounded by alternate long andshort dashed lines indicates a host computer, and a portion surroundedby dotted lines indicates a printer connected to the host computer. Forthe sake of descriptive simplicity, the host computer and the printerare connected in a one-to-one correspondence with each other.

[0129] The image processing apparatus shown in FIG. 22 includes a PDL(page descriptor language) unit 3101, a rasterizer 3102, an encodingunit 3103, and compressed images A (3104), B (3105), and C (3106) storedin the host computer.

[0130] When one page of a document, as shown in FIG. 2, is to be formedby application software of the host computer, text information, i.e.,information indicating areas of characters and graphics except for imageinformation is rasterized and transmitted after being encoded. In thiscase, information indicating image areas is also formed by the PDL 3101and encoded before being transmitted. This information indicating imageareas is information for distinguishing between image areas and theremaining area on the basis of layout information consisting of, e.g.,the start addresses of X and Y coordinates at the start point of eachimage area and the lateral and longitudinal widths of the image. Theinformation indicating image areas is, for example, information of onepage in which “1” is placed at each pixel in image areas and “0” isplaced at each pixel in an area except for the image areas.

[0131] This information will be referred to as a layout planehereinafter.

[0132] In the printer, the received text information, image information,and layout plane are stored in a text memory 3107, an image memory 3108,and a layout plane memory 3109, respectively. Data from the text memoryand the image memory are decoded using a determining unit on the basisof information obtained by decoding the information in the layout planememory.

[0133] That is, upon receiving decoded information as shown in FIG. 6,the determining unit determines that a portion in which 0s are arrangedis an area except for an image area. The determining unit thereforecloses a switch 3114 to a terminal A to decode the text information andtransmits the decoded information to a printer engine 3115.

[0134] On the other hand, determining that a portion in which 1s arearranged is an image area, the determining unit closes the switch 3114to a terminal B and transmits the image information decoded by acompressed image decoding unit 3113 to the printer engine 3115. In thismanner, the determining unit performs the determination in sequence inthe raster direction and transmits the results to the printer engine.

[0135] When a document in which a plurality of compressed images arepasted on one page as shown in FIG. 7A is to be formed, the layout planeas shown in FIG. 7B is obtained in accordance with the above processing.If decoding is performed in sequence in the raster direction by usingthis layout plane, an image area B appears before an image A istransmitted completely. Since no discrimination between these imageareas is performed, the image information of A remaining in the memoryis transmitted to the image area B.

[0136] In this embodiment, therefore, if a plurality of image areas arepresent on one page, layout planes are formed for the individual imagesas shown in FIGS. 23C, 23D, and 23E.

[0137] These layout planes are encoded in the same manner as describedabove and stored in the layout plane memory 3109. The layout planes arethen decoded and supplied to the determining unit. If all the layoutplanes are 0, the determining unit decodes the information in the textmemory 3107, closing the switch 3114 to the terminal A, and transmittingthe decoded information to the printer engine 3115.

[0138] If any of the layout planes is 1, the determining unit selectsone of read registers A, B, and C (3901, 3902, and 3903 in FIG. 24) inthe image memory, which indicates an image corresponding to the layoutplane having 1. The determining unit decodes the information indicatedby the selected register by compressed image coding while updating theregister. The determining unit then closes the switch 3114 to theterminal B and transmits the decoded information to the printer engine3115.

[0139] As described above, it is possible to determine the image area ofeach image because the layout plane is formed for each image, so noinconvenience takes place even if a plurality of image areas are presenton one page.

9th Embodiment

[0140] The ninth embodiment of the present invention will be describedbelow with reference to FIGS. 25, 26A, and 26B.

[0141] The characteristic feature of the present invention is that evenif a plurality of compressed images are pasted in one page, the imageareas of compressed images not overlapping in the main-scanningdirection are presented in the same layout plane. “Not overlapping inthe main-scanning direction” means a state in which only one image areaexists in the main-scanning direction.

[0142] That is, for a document in which compressed images are pasted asshown in FIG. 23A, layout planes as shown in FIGS. 26A and 26B areformed.

[0143]FIG. 25 is a flow chart showing a method of forming these layoutplanes. This flow chart will be described below.

[0144] First, a list of the start addresses and the end addresses in thesub-scanning direction of the image areas of compressed images pasted inone page of a document is generated (step S1).

[0145] Subsequently, it is determined that the image area of the firstimage is arranged in the first plane (step S2). (This plane means alayout plane before the image areas are presented.)

[0146] In step S5, it is checked on the basis of the above-mentionedlist whether each of the second and subsequent images overlaps the imagein the first plane in the main-scanning direction, i.e., whether thestart address and the end address in the sub-scanning direction of oneimage overlap those of other images. If NO in step S5, the image areasof these images are arranged in the first plane (step S6). If YES instep S5, planes which do not overlap the second plane, the third plane,. . . are checked, and a correspondence between the image areas of theimages and the checked planes is determined (step S4). This processingis repeatedly executed until all the images are processed (steps S3 andS7).

[0147] Thereafter, a necessary number of layout planes are formed bydeveloping the layout information of the individual images into theirrespective planes (steps S8 to S11).

[0148] Assume that the image output apparatus shown in FIG. 22 isoperated to transmit the document shown in FIG. 23A to the printerengine while performing determinations in sequence in the rasterdirection by using the layout planes shown in FIGS. 26A and 26B formedby the above method. In this case, transmission of the image area B isstarted before the image area A is completely transmitted. Since,however, these image areas are formed on different layout planes, piecesof image information to be transmitted are switched by the processingdescribed in the above embodiment. The transmission of the imageinformation of A is completed when the image area C appears, so C istransmitted without performing switching. Therefore, the use of the samelayout plane brings about no inconvenience.

[0149] According to this embodiment as described above, the processingactivity for decoding can be simplified by transferring informationwhich discriminates between image areas and an area except for images tothe image output apparatus.

10th Embodiment

[0150] The 10th embodiment of an image processing apparatus according tothe present invention will be described in detail below with referenceto FIGS. 27 and 30A to 30C.

[0151] Referring to FIG. 27, a portion surrounded by alternate long andshort dashed lines indicates a host computer, and a portion surroundedby dotted lines indicates a printer. For the sake of descriptivesimplicity, assume that the host computer and the printer are connectedin a one-to-one correspondence with each other.

[0152] The image processing apparatus shown in FIG. 27 includes a PDL(page descriptor language) unit 5101, a rasterizer 5102, an encodingunit 5103, and a compressed image 5104 stored in the host computer. Thedetails of these units 5101 to 5104 are the same as those inconventional examples.

[0153] When one page of a document, as shown in FIG. 2, is to be formed,text information and graphic information indicating graphics, except forimage information, are rasterized and transmitted after being encoded inthe same manner as in conventional apparatuses. At the same time, layoutplane information indicating an image area and an SOI plane are alsoformed by the PDL 5101, encoded together with the text information bythe encoding unit 5103, and transmitted to the printer through aselector 5105 and a cable 5106. Image information, on the other hand, istransmitted in a compressed state to the printer.

[0154] In the printer, the received text information and imageinformation are stored in a text memory 5108 and an image memory 5109,respectively.

[0155] The text information, the layout plane information, and the SOIplane information stored in the text memory are decoded simultaneouslyby a text decoding unit 5111. The decoded text information, layout planeinformation, and SOI plane information are supplied to signal lines5120, 5121, and 5122, respectively.

[0156] The location of the image information is determined on the basisof the layout plane information of the above three pieces of informationdecoded at the same time.

[0157] As an example, if the layout plane information is the one shownin FIG. 3, an image is arranged in the area of “1” surrounded by dottedlines.

[0158] The image information arranged at this position can be obtainedby decoding the compressed image information stored in the image memory5109 by an image decoding unit 5112. The operation of this imagedecoding unit is controlled by the above layout plane information. Thatis, the image decoding unit performs decoding when the value of thelayout plane information is “1” and stops the decoding operation whenthe value is “0”.

[0159] A selector 5113 is also controlled by the layout planeinformation. That is, decoded image information is supplied to a printerengine 5114 when the decoding operation is performed. When, in contrast,no decoding is performed, the output from the text decoding unit 5111 issupplied to the printer engine 5114.

[0160] If a plurality of images to be decoded are present, control fordetermining which image is to be decoded is necessary in addition to theabove control. Units for performing this control are an imageidentification signal generating unit 5115 and a memory managing unit5110.

[0161] The memory managing unit 5110 manages a correspondence betweenthe number of each compressed image information and a location (address)of the image memory 5109 at which the information is stored. The memorymanaging unit 5110 reads out, from the image memory 5109, compressedimage information corresponding to an image number supplied from theimage identification signal generating unit, and supplies the readoutimage information to the image decoding unit 5112.

[0162] The image identification signal generating unit 5115 identifiesthe number of each image to be decoded by the image decoding unit 5112.The number of each image cannot be identified by the above-mentionedlayout plane information alone although the location of the image can beknown by that information.

[0163] The SOI plane, therefore, is used for this purpose.

[0164] As shown in FIG. 28, the SOI plane is bit map information inwhich the start position (the upper left position) of an image isrepresented by “1”, and the other area of the image is represented by“0”. The value of an area in which no image is arranged is naturally“0”.

[0165] The number of “1”s is equal to the number of images to bearranged, so the number of “1”s is N if N images are to be arranged inone page.

[0166] On the basis of information of “1” on this SOI plane, the imageidentification signal generating unit 5115 generates the number of eachimage to be arranged.

[0167]FIG. 29 is a block diagram showing the image identification signalgenerating unit 5115.

[0168] Referring to FIG. 29, the image identification signal generatingunit 5115 includes an input terminal 1501 for receiving the SOI planeinformation, an input terminal 1502 for receiving the layout planeinformation, an m-bit counter 1503 for detecting and counting “1”s inthe SOI plane, an m-bit wide FIFO memory 1504 with a capacitycorresponding to pixels in the main-scanning direction, a mask circuit1505 for masking an m-bit output from the FIFO memory to zero, aselector 1506 for performing switching between the outputs from the maskcircuit and the counter, an output terminal 1507 for delivering an imagenumber, a NOT element 1508, and two-input NAND elements 1509 and 1510constituting an R-S flip-flop. This R-S flip-flop generates an outputsignal 1511.

[0169] Suppose layout plane information shown in FIG. 30A and SOI planeinformation shown in FIG. 30B are input to the image identificationsignal generating unit with the above arrangement. Each inputinformation is raster-scanned from the upper left corner of a page.

[0170] First, the counter 1503 is cleared to zero by a circuit (notshown), and the output signal 1511 from the R-S flip-flop is also set atlevel Low. “0”s are successively input for each plane until the positionof the first image is reached. While “0”s are input, an m-bit signalmasked to zero by the mask circuit 1505 is kept supplied to the imagenumber output terminal 1507.

[0171] When the position of the first image A is reached, the SOI planeinformation goes to “1”, and the counter 1503 counts up to “1”. Also,the R-S flip-flop is set to set the output signal 1511 at level High.

[0172] As a result, the output signal value “1” from the counter 1503 isselected as an image number by the selector 1506 and supplied to theterminal 1507. The output from the selector 1506 is also input to theFIFO memory 1504.

[0173] The value of the layout plane information remains “1” for sometime immediately after the SOI plane information goes to “1”, andreturns to “0” when the dimension of the image in the lateral directionis exceeded. Therefore, the R-S flip-flop is reset to set the outputsignal 1511 at level Low, and the m-bit signal masked to zero by themask circuit 1505 is output again.

[0174] As the scan proceeds further, the position of the next image B isreached, and the SOI plane information goes to “1” again. The value ofthe counter 1503 goes this time to “2”, and this value is supplied as animage number to the terminal 1507 via the selector 1506. This output isalso applied to the FIFO memory 1504.

[0175] As with the image A, the above state continues until thedimension of the image in the lateral direction is exceeded. Scanning onthat line is then finished, and scanning on the next line is started.

[0176] Since there is no “1” in the SOI plane information for the nextline, the image identification signal generating unit 5115 is controlledby the layout plane information alone. The image number of theimmediately preceding line is already stored in the FIFO memory 1504.This image number is read out from the FIFO at a timing accuratelydelayed by one line.

[0177] The readout image number information is applied to the maskcircuit 1505. Since, however, the layout plane information is “1” in theimage area, this image number information passes through the maskcircuit without being masked. As a result, the same image numberinformation as for the immediately preceding line is output from theterminal 1507 via the selector 1506. This output information is inputagain to the FIFO memory 1504.

[0178] The above processing is repeatedly executed for both the images Aand B as long as their respective image areas continue vertically(downward).

[0179] Subsequently, scanning is started for the line next to the end ofthe area of the image A. At this point, the image number correspondingto the image A is still stored in the FIFO memory 1504. The layout planeinformation input from the terminal 1502, however, has no informationindicating the area of the image A, i.e., the input signal from theterminal 1502 remains “0”.

[0180] The m-bit signal read out from the FIFO memory 1504 after beingdelayed by one line is therefore masked to zero by the mask circuit 1505and output to the terminal 1507 via the selector 1506. Since the area ofthe image B continues, on the other hand, the layout plane informationapplied from the terminal 1502 goes to “1” when the scan has reachedthat area. Consequently, the image number corresponding to the image Bstored in the FIFO memory 1504 passes through the mask circuit 1505without being masked and is output from the terminal 1507 via theselector 1506.

[0181] The above processing is repeatedly performed for the area of theimage B as long as the area continues vertically. In scanning the linenext to the end of the area of the image B, similar to the processingfor the image A, the output image number from the FIFO memory 1504 ismasked to zero by the mask circuit 1505 and output from the terminal1507.

[0182] At the time the scanning for that line is finished, all thecontents of the FIFO memory 1504 are cleared to zero. This statecontinues until a subsequent image area, i.e., an area in which the SOIplane information is “1” is reached.

[0183] When the area of the image C is reached as the line scanproceeds, the SOI plane information goes to “1”, and the counter 1503counts up to “3”. Also, the R-S flip-flop is set to set the outputsignal 1511 at level High.

[0184] The subsequent processing is exactly the same as those explainedabove for the images A and B. That is, the image number of the image Cis output from the terminal 1507 only in an area corresponding to theimage area of the image C.

[0185] As a result, the image number information shown in FIG. 30C isgenerated by the image identification signal generating unit 5115 on thebasis of the layout plane information shown in FIG. 30A and the SOIplane information shown in FIG. 30B. This image number information issupplied to the memory managing unit 5110, thereby reliably arrangingthe corresponding images.

11th Embodiment

[0186] The 11th embodiment of the present invention will be described indetail below with reference to FIG. 31.

[0187] In this embodiment, another arrangement of the imageidentification signal generating unit 5115 shown in FIG. 27 will bedescribed. Therefore, any other arrangement of the system of thisembodiment is the same as that shown in FIG. 27, and so a description ofthe operation of the system will be omitted.

[0188] In FIG. 31, the same reference numerals as in FIG. 29 denoteblocks or I/O terminals with the same functions, and a detaileddescription thereof will be omitted.

[0189] In FIG. 31, blocks different from those shown in FIG. 29 are azero detecting unit 1901 and a two-input AND element 1902.

[0190] The zero detecting unit 1901 detects that all bits of an m-bitsignal from a FIFO memory 1504 are “0”. This detection result indicatesthat an immediately preceding line is not an area of an image.

[0191] The two-input AND element 1902 ANDs the detection result andinput layout plane information from a terminal 1502, thereby indicatingthat an area of an image starts from a line currently being scanned.This AND result is supplied to a signal line 1903.

[0192] In this embodiment, it is required to first clear a counter 1503and clear the FIFO memory 1504 to zero.

[0193] Assume, as in the above embodiment, that the layout planeinformation shown in FIG. 30A and the SOI plane information shown inFIG. 30B are input to the image identification signal generating unit.

[0194] First, “0”s are kept input for both the planes until the positionof the first image is reached. While “0”s are kept input, the signalline 1903 is at level Low, and so the m-bit output signal (whose valueis of course zero) from a mask circuit 1505 is output to an image numberoutput terminal 1507.

[0195] When the position of the first image A is reached, the SOI planeinformation goes to “1”, and the counter 1503 counts up to “1”.

[0196] At this point, the layout plane information is also “1”. Inaddition, since the m-bit output from the FIFO memory 1504 is zero, thisoutput is detected by the zero detecting unit 1901, and the outputsignal 1903 from the AND element 1902 goes to level High.

[0197] Consequently, the value “1” of the output signal from the counter1503 is selected as an image number by a selector 1506 and output to theterminal 1507. The output from the selector 1506 is also input to theFIFO memory 1504.

[0198] The value of the layout plane information remains “1” for sometime immediately after the SOI plane information goes to “1”, andreturns to “0” when the dimension of the image in the lateral directionis exceeded. As a result, the output signal 1903 from the AND element1902 goes to level Low, and the m-bit signal masked to zero by the maskcircuit 1505 is output again.

[0199] As the scan proceeds further, the position of the next image B isreached, and the SOI plane information goes to “1” again. The value ofthe counter 1503 goes this time to “2”, and this value is output as animage number to the terminal 1507 via the selector 1506. This output isalso input to the FIFO memory 1504.

[0200] As with the image A, the above state continues until the lateraldimension of the image is exceeded. When this lateral dimension isexceeded, the output from the terminal 1507 returns to zero. Scanning onthat line is then finished, and scanning for the next line is started.

[0201] The image number of the immediately preceding line is alreadystored in the FIFO memory 1504. This image number is read out from theFIFO at a timing accurately delayed by one line. In each image area,these readout contents represent an image number except for zero, whichcorresponds to the image. In an area other than the image areas, thecontent is zero.

[0202] The zero detection timing of the zero detecting unit 1901 istherefore exactly opposite to the timing at which the layout planeinformation goes to “1”. For this reason, the output signal 1903 fromthe AND element is at level Low at any instant, and so the output fromthe mask circuit 1505 is output to the image number output terminal 1507via the selector 1506.

[0203] The above processing is executed repeatedly for both the images Aand B as long as their respective image areas continue vertically(downward).

[0204] Subsequently, scanning is started for the line next to the end ofthe area of the image A. At this point, the image number correspondingto the image A is still stored in the FIFO memory 1504. However, thelayout plane information input from the terminal 1502 has no informationindicating the area of the image A, i.e., the input signal from theterminal 1502 remains “0”.

[0205] The m-bit signal read out from the FIFO memory 1504 after beingdelayed by one line is therefore masked to zero by the mask circuit 1505and output to the terminal 1507 via the selector 1506.

[0206] Since the area of the image B still continues, on the other hand,the input layout plane information from the terminal 1502 goes to “1”when scanning has reached that area. Therefore, the image numbercorresponding to the image B stored in the FIFO memory 1504 passesthrough the mask circuit 1505 without being masked and is output fromthe terminal 1507 via the selector 1506.

[0207] Thereafter, the above processing is repeatedly executed for thearea of the image B as long as the area continues vertically. Inscanning the line next to the end of the area of the image B, similar tothe processing for the image A, the output image number from the FIFOmemory 1504 is masked to zero by the mask circuit 1505 and output fromthe terminal 1507.

[0208] At the time the scan for that line is finished, all the contentsof the FIFO memory 1504 are cleared to zero. This state continues untila subsequent image area, i.e., an area in which the SOI planeinformation is “1” is reached.

[0209] When the area of the image C is reached as the line scanproceeds, the SOI plane information goes to “1”, and the counter 1503counts up to “3”. In addition, the zero detecting unit 1901 detects thezero output from the FIFO memory 1504, and “1” is input as the layoutplane information. Therefore, the signal 1903 is set at level High.

[0210] The subsequent processing is exactly the same as those for theimages A and B described above. That is, the image number of the image Cis output from the terminal 1507 only in an area corresponding to thearea of the image C.

[0211] As a result, the image number information shown in FIG. 30C isgenerated by the image identification signal generating unit shown inFIG. 31 on the basis of the layout plane information shown in FIG. 30Aand the SOI plane information shown in FIG. 30B. This image numberinformation is supplied to the memory managing unit 5110 shown in FIG.27, thereby reliably arranging the corresponding images.

[0212] According to this embodiment as described above, the layout planeinformation indicating areas of images and the SOI plane informationindicating the start positions of these images are generatedsimultaneously with PDL development. The text information obtained bythe PDL development and the above information are encoded by the sameencoding unit and transferred from a host computer to a printer. Thesepieces of information are decoded on the printer side.

[0213] On the basis of the layout plane information and the SOI planeinformation thus decoded, the image identification signal is generatedby the image identification signal generating unit. This facilitatesmanagement of the layout of a plurality of images.

[0214] Consequently, flexible functions can be realized at a lower costthan in conventional systems.

12th Embodiment

[0215] The following drawbacks are found in printer systems in which ahost computer generates printer descriptor language (PDL) programs andbit map images and transmits these pieces of information to a printer,and a controller of the printer develops and arranges the transmittedinformation to form hard copies, among other printer systems describedin the conventional examples mentioned earlier.

[0216] (1) Transmission of the bit map images from the host computer tothe printer is time-consuming or requires a wide-band transmission pathbecause the quantity of the bit map images is very large.

[0217] (2) Fonts are required for both the host computer and the printerin developing codes. That is, a unit for this purpose cannot be sharedby the host computer and the printer.

[0218] (3) A program developing unit of the printer is constituted byfirmware and hence cannot be graded up.

[0219] (4) The program developing unit of the printer is constituted byfirmware and hence has no expansibility.

[0220] (5) Since the operating ratio of the printer is generally lowerthan that of the host computer, the hardware resource of the printercannot be used effectively.

[0221] In consideration of the above drawbacks, this embodiment adoptsan arrangement as shown in FIG. 32. Referring to FIG. 32, an applicationprogram 4001 forms a document while exchanging files required indocument formation through a communication line 4002 and a communicationmanager 4003.

[0222] The document thus formed can be displayed on a monitor TV 4007via an OS 4004, an image manager 4005, and a CRT driver 4006. It is alsopossible to transmit the document to a printer section via a devicedriver, thereby obtaining hard copies by using an engine controller4009, an engine I/F 4010, and a printer engine 4011.

[0223]FIG. 33 is a block diagram showing the details of the imagemanager 4005. The image manager 4005 receives the document filegenerated by the application via the OS 4004. The document file consistsof a PDL file and an image compressed file. The PDL file is developedinto a developed memory 4015 by an interpreter 4012 and a rasterizer4013 by using fonts stored in a font unit 4014.

[0224] The image information is received in the form of a compressedfile and expanded by an image expanding unit 4016. The PDL file containsthe edit command and the attribution of this image file. The interpreter4012 separates these pieces of information from the PDL file, and theattribution information thus separated is stored in an image attributionmemory 4017. Primary conversion is performed for the image by an editprocessing unit 4018 and a work memory 4019 in accordance with the editcommand, and the converted result is written in the developed memory4015. The contents of the developed memory 4015 are sequentiallysupplied to the monitor TV 4001 via the CRT driver 4006 and monitored byan operator.

[0225] A layout control signal is stored in a layout memory 4020. Thefinal document is generated in the developed memory 4015 by theseprocessing activities. Characters and line drawings, highly effectivelycompressed images, layout information, and image attribution informationare obtained from the image manager 4005.

[0226] The function of the device driver is shown in FIG. 34. Thecharacter/line drawing information, the layout information, and theimage attribution information supplied from the image manager 4005 aremultiplexed by a multiplexer 4021 and compressed by a losslesscompressing unit 4022 in a lossless (reversible) manner. These(compressed) signal and image are further multiplexed by a multiplexer4023 and transmitted to the printer section via a communicating unit4024.

[0227] The function of the engine controller 4009 of the printer sectionis shown in FIG. 35. The signal transmitted from the host computersection is received by a communicating unit 4025 and separated into thecharacter/Line drawing information, the layout information, the imageattribution information, and the image (compressed) information by ademultiplexer 4026. The character/line drawing information, the layoutinformation, and the image attribution information are stored in amemory 1, and the image (compressed) information is stored in a memory2.

[0228] A decoder 1 expands the character/line drawing information, and adecoder 2 expands the image (compressed) information. The layoutinformation and the image attribution information are also decoded bythe decoder 1. The layout information is used to control a synthesizingunit 4027, and the image attribution information is used to control aresolution converting unit 4028. The former unit synthesizes thecharacter/line drawing information and the image information, and thelatter unit converts the dot density of the image file into theresolution of the engine. These processing activities are performed inreal time by a timing signal generating unit 4029 in synchronism withthe operation of the engine.

13th Embodiment

[0229]FIG. 36 shows another embodiment of the device driver. Whencharacter/line drawing information is binary, its information quantityis small. In this case, since the quantities of layout information andimage attribution information are also small, the cost performance mayimprove if no compression is performed. In such a case, thecharacter/line drawing information, the layout information, the imageattribution information, and the image (compressed) information aredirectly multiplexed by a multiplexer 4030 and transmitted to a printersection via a communicating unit 4031.

[0230] This makes it unnecessary the character/line drawing informationexpanding function of the decoder 1 in the engine controller of theprinter section, thereby reducing the size of the hardware.

[0231] According to the 12th and the 13th embodiments of the present;invention as described above, since the information is exchanged in theform of compressed data between the host computer and the printer, thetransmission time can be shortened. In addition, development into bitmap images is performed only by the host computer, so fonts required inthe development need only be provided in the host computer. Since theunit that is conventionally necessary in the printer is no longerrequired, the resource can be utilized effectively. Furthermore, theframe memory provided in the printer need only have a capacity meetingthe compression ratio, and this reduces the cost of the overallapparatus. When the processing activities of the host computer areperformed in a multitask manner such that the rasterizing processing isalso executed as one task, the efficiency of the host computer can befurther improved.

[0232] As has been described above, each embodiment of the presentinvention makes it feasible to perform highly efficient transfer andreproduction of images in performing image fitting.

[0233] The present invention is not limited to the above embodiments butcan be modified without departing from the scope of the appended claims.

What is claimed is:
 1. An image processing apparatus comprising: outputmeans for outputting image information to be used in editing and areainformation for performing editing by using the image information; andtransmitting means for transmitting the image information an the areainformation output from said output means, wherein said output meansoutputs the area information developed for each image in the form ofcompressed data.
 2. An apparatus according to claim 1, wherein the imageinformation is compressed image data.
 3. An apparatus according to claim2, wherein the image information and the area information are encoded bythe same method.
 4. An apparatus according to claim 1, wherein the imageinformation is separated into a natural image and a line drawing.
 5. Anapparatus according to claim 1, wherein the area information containsinformation of a plurality of areas.
 6. An apparatus according to claim1, wherein the image information is formed by a page descriptorlanguage.
 7. An image processing apparatus comprising: generating meansfor generating first image information representing a natural image,second image information representing a line drawing, and areainformation for performing editing by using the first image informationand the second image information; and encoding means for synthesizingthe second image information and the area information generated by saidgenerating means and encoding the synthesized information.
 8. An imageprocessing apparatus comprising: a host computer for processing imageinformation; and a printer for forming a visible image of the imageinformation processed by said host computer, wherein said host computerperforms irreversible compression for image information representing anatural image in units of pixels and reversible compression for imageinformation representing a line drawing in units of pixels, andtransmits the compressed image information to said printer.
 9. An imageprocessing method of decoding image information described by a pagedescriptor language, developing the decoded image information, andtransmitting the developed image information to a printer, comprisingthe steps of: developing, by the page descriptor language, the imageinformation described by the page descriptor language into a form notpasted with to-be-pasted image information, without reading out, forimage development, the to-be-pasted image information from means forstoring the to-be-pasted image information; and separately transmittingto said printer the image information in the form not pasted with theto-be-pasted image information and the to-be-pasted image information.10. A method according to claim 9, wherein the image information in theform not pasted with the to-be-pasted image information is transmittedto said printer after being compressed.
 11. A method according to claim10, wherein the image information in the form not pasted with theto-be-pasted image information is compressed by reversible coding.
 12. Amethod according to claim 10, wherein the to-be-pasted image informationis compressed by irreversible coding.
 13. A method according to claim 9,wherein bit map information indicating a position at which theto-be-pasted image information described by the page descriptor languageis to be pasted is generated on the basis of information indicating thepasting position and transmitted to said printer.
 14. A method accordingto claim 13, wherein the bit map information is processed such that theto-be-pasted image information is pasted after being varied or rotated.15. A method according to claim 13, wherein the bit map information istransmitted to said printer after being encoded.
 16. A method accordingto claim 15, wherein the bit map information and the image informationin the form not pasted with the to-be-pasted image information areencoded by common encoding means.
 17. A method according to claim 13,wherein the bit map information represents identification informationfor the to-be-pasted image information in correspondence with pixelsindicating the to-be-pasted image information, and second bit mapinformation representing color information in correspondence with pixelsnot indicating the to-be-pasted image information is transmitted to saidprinter.
 18. An image output system, wherein first bit map informationindicating an area of an image to be pasted and second bit mapinformation indicating a start position of the image to be pasted aregenerated by a host computer during PDL development, text/graphicinformation obtained by the PDL development and the first and second bitmap information are encoded by a common encoding circuit and transferredfrom said host computer to a printer, and said printer performs decodingto generate information of the arrangement of a plurality of images fromthe first and second bit map information, thereby controlling the layoutof said plurality of images.
 19. A system according to claim 18, whereinthe information of the arrangement of said plurality of images isinformation indicating in units of pixels which one of said plurality ofimages to be pasted is to be arranged.
 20. A system according to claim19, wherein the information in units of pixels is a number correspondingto each image to be pasted when said plurality of images to be pastedare numbered from “1”.